Engine-driven cutter

ABSTRACT

A handheld engine-driven cutter is provided with a disk blade and a main body that drives the disk blade. The main body comprises a four-stroke engine, an oil supplying opening from which engine oil is supplied, and an oil exhausting opening from which the engine oil is exhausted. In this engine cutter, the oil supplying opening and the oil exhausting opening are both disposed on one side of the main body where one end of a driving axis of the four-stroke engine is located.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No.2010-46694 filed on Mar. 3, 2010, the contents of which are herebyincorporated by reference into the present application.

TECHNICAL FIELD

The present invention relates to a handheld engine-driven cutter thatdrives a disk blade by an engine.

DESCRIPTION OF RELATED ART

Japanese Patent Application Publication No. 2007-528792 discloses ahandheld engine-driven cutter. The engine-driven cutter comprises a diskblade and an engine that drives the disk blade, and is used e.g. forcutting concrete and steel materials at a building site. A two-strokeengine is used as the foregoing engine. The two-stroke engine isadvantageous over other types of engines in that its structure is simpleand its size is small. Thus, the two-stroke engine is used in thehandheld engine-driven cutter for downsizing and cost reduction.

Nevertheless, the two-stroke engine has a problem in that its emissionof unburned gas is high, and its adverse effect on the naturalenvironment is relatively great. Demands for environmental performanceare also increasing with handheld engine-driven cutters, and it isdifficult for the conventional products adopting the two-stroke engineto satisfy the high level of environmental performance that is beingdemanded.

BRIEF SUMMARY OF INVENTION

In light of the foregoing circumstances, a use of a four-stroke enginein substitute for the two-stroke engine in the handheld engine-drivencutter may be considered. With the four-stroke engine, since its intakeport and exhaust port are respectively opened and closed with a valveoperating mechanism, there is an advantage in that the emission ofunburned gas is low and it is energy-efficient in comparison to thetwo-stroke engine in which the ports are opened and closed respectivelywith a piston. In particular, with a separate lubrication systemfour-stroke engine, since a large amount of engine oil is subject tocyclic use within the engine and the amount of engine oil that isconsumed together with fuel is extremely small, the environmentalperformance can be improved even further.

However, with the separate lubrication system four-stroke engine, unlikea mixed lubrication system two-stroke engine or a four-stroke enginethat uses fuel with engine oil mixed therein, the engine oil needs to besupplied separately from the fuel. Moreover, the engine oil needs to bereplenished and replaced in an adequate frequency. Thus, if the separatelubrication system four-stroke engine is adopted in the engine-drivencutter, it is anticipated that a user who has been using theconventional product will have trouble or even be unsuccessful inreplacing the engine oil due to inexperience.

Accordingly, an object of this invention is to provide teachings forfacilitating the replacement of the engine oil in the engine-drivencutter mounted with the four-stroke engine.

In one aspect of the present teachings, a handheld engine-driven cuttercomprises a disk blade, and a main body that drives the disk blade. Themain body comprises a four-stroke engine, an oil supplying opening fromwhich engine oil is supplied, and an oil exhausting opening from whichthe engine oil is exhausted. This engine-driven cutter has the oilsupplying opening and the oil exhausting opening disposed on one side ofthe main body.

If the oil supplying opening and the oil exhausting opening are bothdisposed on the same side of the main body, the user can replace theengine oil without having to change the direction of the engine-drivencutter or change one's position relative to the engine-driven cutter.Moreover, since the oil supplying opening and the oil exhausting openingcan be visually confirmed simultaneously, it is possible to prevent amistake such as continuing to supply the engine oil from the oilsupplying opening while forgetting to close the oil exhausting opening.If the oil supplying opening and the oil exhausting opening are disposedon one side of the main body, the user can comfortably performoperations without having to mind the oil supplying opening or the oilexhausting opening by using the engine-driven cutter while being in aposition on the other side of the main body.

According to the aforementioned structure, it is possible to realize anengine-driven cutter mounted with a four-stroke engine in which thereplacement of the engine oil is facilitated (easy to understand).Moreover, it is possible to realize an engine-driven cutter that can beused by the user comfortably without having to mind the existence of theoil supplying opening and the oil exhausting opening.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a view of an engine-driven cutter from a right side(driving side).

FIG. 2 shows a plan view of the engine-driven cutter from above.

FIG. 3 is a cross sectional view of line in FIG. 1.

FIG. 4 is a partial cross sectional view of a main body of theengine-driven cutter.

FIG. 5 shows an assembly structure of a casing main body and a filterbracket and a filter cover.

FIG. 6 is another view of the assembly structure of the casing main bodyand the filter bracket and the filter cover from a different directionfrom that of FIG. 5.

FIG. 7 shows an assembly structure of a filter bracket and a carburetorand a carburetor mount.

FIG. 8 shows a positional relationship of a carburetor arm and a recessportion of the carburetor mount.

FIG. 9 shows a connection structure of the filter bracket and thecarburetor and the carburetor mount.

FIG. 10 shows the connection structure of the filter bracket and thecarburetor and the carburetor mount from a different direction from thatof FIG. 9.

FIG. 11 shows a state where an oil separator and a breathing tube aremutually connected via a through hole of a seal member,

FIG. 12 shows an assembly structure of a throttle lever and a switchlever.

FIG. 13 is an exploded view of an assembly structure of the throttlelever and the switch lever.

FIG. 14 shows a guard from the right side.

FIG. 15 shows the guard from a front side.

FIG. 16 shows the guard from a bottom side.

FIG. 17 is a cross sectional view of line XVII-XVII in FIG. 14.

FIG. 18 is a cross sectional view of line XVIII-XVIII in FIG. 16.

FIG. 19 shows a state where the engine-driven cutter is fully angledtowards a surface of a workpiece.

DETAILED DESCRIPTION OF INVENTION

In one embodiment of the present teachings, the main body may furthercomprise a fuel supplying opening from which fuel is supplied. In theforegoing case, preferably, the fuel supplying opening is also disposedon the one side of the main body as with the oil supplying opening andthe oil exhausting opening. According to this structure, the uservisually confirms the oil supplying opening and the fuel supplyingopening simultaneously. Consequently, it is possible to prevent the userfrom erroneously supplying the fuel to the oil supplying opening orerroneously supplying the engine oil to the fuel supplying opening. Inaddition, the user can comfortably perform operations without having tomind the existence of the oil supplying opening, the oil exhaustingopening, and the fuel supplying opening by using the engine-drivencutter while being in a position on the other side of the main body.

In one embodiment of the present teachings, the main body may furthercomprise a starter member that is operated by the user to start thefour-stroke engine. In the foregoing case, preferably, the startermember is also disposed on the one side of the main body as with the oilsupplying opening and the oil exhausting opening. According to theforegoing structure, the user can comfortably perform operations withouthaving to mind the existence of the oil supplying opening, the oilexhausting opening, and the starter member by using the engine-drivencutter while being in the position on the other side of the main body.

In one embodiment of the present teachings, the main body may furthercomprise a transmission mechanism that supports the disk blade andtransmits torque of the four-stroke engine to the disk blade. In theforegoing case, preferably, the transmitting mechanism is also disposedon the one side of the main body as with the oil supplying opening andthe oil exhausting opening. According to the foregoing structure, theuser can comfortably perform operations without having to mind theexistence of the oil supplying opening, the oil exhausting opening, andthe transmitting mechanism by using the engine-driven cutter while beingin the position on the other side of the main body.

Representative, non-limiting examples of the present invention will nowbe described in further detail with reference to the attached drawings.This detailed description is merely intended to teach a person of skillin the art further details for practicing preferred aspects of thepresent teachings and is not intended to limit the scope of theinvention. Furthermore, each of the additional features and teachingsdisclosed below may be utilized separately or in conjunction with otherfeatures and teachings to provide improved engine-driven cutters.

Moreover, combinations of features and steps disclosed in the followingdetail description may not be necessary to practice the invention in thebroadest sense, and are instead taught merely to particularly describerepresentative examples of the invention. Furthermore, various featuresof the above-described and below-described representative examples, aswell as the various independent and dependent claims, may be combined inways that are not specifically and explicitly enumerated in order toprovide additional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intendedto be disclosed separately and independently from each other for thepurpose of original written disclosure, as well as for the purpose ofrestricting the claimed subject matter, independent of the compositionsof the features in the embodiments and/or the claims. In addition, allvalue ranges or indications of groups of entities are intended todisclose every possible intermediate value or intermediate entity forthe purpose of original written disclosure, as well as for the purposeof restricting the claimed subject matter.

Embodiment

Examples of an engine-driven cutter are explained below with referenceto the appended drawings. FIG. 1 is a side view of an engine-drivencutter 10, and FIG. 2 is a plan view of the engine-driven cutter 10.Moreover, FIG. 3 is a cross sectional view of line in FIG. 1. Theengine-driven cutter 10 comprises a disk blade 12, and a main body 14that drives the disk blade 12. The disk blade 12 can cut lithicmaterials and metal materials, and the engine-driven cutter 10 is usede.g. for cutting concrete and steel materials at a building site.

As shown in FIG. 1 and FIG. 2, when the engine-driven cutter 10 ismounted on a horizontal plane H, the disk blade 12 is positioned on oneside of the horizontal direction relative to the main body 14. In theensuing explanation, a state where the engine-driven cutter 10 ismounted on the horizontal plane H is used as the reference, and one sideof the horizontal direction where the disk blade 12 is positionedrelative to the main body 14 is referred to as a front side, and theopposite direction thereof is referred to as a rear side. Moreover, thevertical upward direction is simply referred to as an upper side and thevertical downward direction is simply referred to as a lower side. Inaddition, as shown in FIG. 2, one side of the horizontal direction thatis perpendicular to the front-back direction is referred to as a leftside and the other side of the horizontal direction perpendicular to thefront-back direction is referred to as a right side. For example, thedisk blade 12 is positioned in front of the main body 14, and itsrotating axis extends in the left-right direction and perpendicular tothe horizontal plane H at the upper side of the horizontal plane H.

The main body 14 is provided with a front handle 16 and a rear grip 28.The front handle 16 is formed with a pipe material, and, in addition tobeing a handle to be grasped by the user, it also functions as a framefor ensuring the strength of the main body 14. The front handle 16extends from the upper side to the left side of the main body 14 at thefront part of the main body 14. The rear grip 28 is provided in thelower rear part of the main body 14. The rear grip 28 extends in a loopshape from the main body 14. The rear grip 28 is provided with anoperation switch such as a throttle lever 30. Moreover, the lower partof the rear grip 28 is provided with a rear foot part 38.

Normally, the user grasps the front handle 16 with one's left hand, andgrasps the rear grip 28 with one's right hand to hold the engine-drivencutter 10. The user moves the engine-driven cutter 10 relative to theworkpiece and cuts the workpiece with the disk blade 12. As describedabove, the engine-driven cutter 10 of this embodiment is a handheldengine-driven cutter that is held by the user. Here, when the user holdsthe engine-driven cutter 10 as described above, the user is positionedon the left side of the main body 14. Normally, since the user ispositioned on the left side of the engine-driven cutter 10, the leftside of the engine-driven cutter 10 is also referred to as the userside.

The main body 14 comprises an engine 18 that drives the disk blade 12.The engine 18 is a four-stroke reciprocating engine. With thefour-stroke engine, since an intake port and an exhaust port arerespectively opened and closed with a valve operating mechanism, thereis an advantage in that the emission of unburned gas is low and it isenergy-efficient (low fuel consumption) in comparison to a two-strokeengine in which such ports are opened and closed respectively with apiston. Since the engine-driven cutter 10 adopts the four-stroke engine18, its environmental performance is considerably improved.

Since the engine 18 is a separate lubrication system four-stroke engine,unlike a mixed lubrication-type two-stroke engine. The engine oil needsto be supplied separately from the fuel. Moreover, the engine oil needsto be replenished and replaced at an adequate frequency. Thus, theengine 18 is provided with an oil supplying opening 18 a to which theengine oil is fed, and an oil exhausting opening 18 b for exhausting theengine oil.

Note that the engine 18 is not limited to the separate lubricationsystem four-stroke engine, and it may also be a mixed lubrication systemfour-stroke engine. However, the separate lubrication system four-strokeengine has an advantage in that it yields superior environmentalperformance in comparison to the mixed lubrication system four-strokeengine, since a large amount of engine oil is subject to cyclic use inthe engine, and the amount of engine oil that is consumed together withthe fuel is extremely small. Moreover, running costs to be borne by auser can also be reduced since the consumption of the engine oil isreduced. Furthermore, if the mixed lubrication system four-stroke engineis employed in a case where the engine-driven cutter 10 is not used fora long period of time, the fuel in the carburetor will evaporate causingonly the engine oil to remain therein, and the carburetor may becomeclogged. With respect to this point, by adopting the separatelubrication system four-stroke engine, the effect of being able to avoidthis kind of problem can also be expected.

The main body 14 comprises a cutter arm 56 mounted on the disk blade 12.The cutter arm 56 is provided on the right side of the main body 14, andextends toward the front side of the main body 14. As shown in FIG. 3,the cutter arm 56 comprises a first plate 56 b fixed to the engine 18and a second plate 56 c fixed to the first plate 56 b, and the secondplate 56 c is provided with a tool shaft 56 e for rotatably supportingthe disk blade 12.

Moreover, the cutter arm 56 comprises a drive pulley 56 a fixed to thedriving axis (crank shaft) 18 c of the engine 18, a driven pulley 56 ffixed to the tool shaft 56 e, and a transmission belt 56 d placed acrossthe drive pulley 56 a and the driven pulley 56 f. Consequently, torqueoutput by the engine 18 is transmitted to the tool shaft 56 e, and thedisk blade 12 is rotatably driven by the engine 18. Accordingly, thecutter arm 56 is also a transmission mechanism for transmitting thetorque output by the engine 18 to the disk blade 12. The right side ofthe main body 14 to which the cutter arm 56 as the transmittingmechanism is provided is generally referred to as the driving side.Here, the position for mutually fixing the first plate 56 b and thesecond plate 56 c is adjustable, and the tension of the transmissionbelt 56 d can be adjusted. Note that the driving axis 18 c of the engine18 and the tool shaft 56 e are mutually parallel, and they both extendin the left-right direction. Moreover, the cutter arm 56 is providedwith a disk blade cover 58 for covering the disk blade 12.

The main body 14 comprises a recoil starter 44 for the user to start theengine 18. The recoil starter 44 is provided on the right side of themain body 14, and provided above the cutter arm 56. As shown in FIG. 3,the driving axis 18 c of the engine 18 extends by passing through thedrive pulley 56 a, and the recoil starter 44 is connected to the distalend of the driving axis 18 c. The recoil starter 44 is provided with astarter lever 42 to be operated by the user. When the user pulls thestarter lever 42, the driving axis 18 c of the engine 18 rotates and theengine 18 is started.

The main body 14 comprises a guard 50. The guard 50 is provided on thelower front side of the main body 14. The lower front side of the mainbody 14 is a position where chips of a workpiece scatter from the diskblade 12, and the guard 50 repels the scattered chips of the workpiecetoward the lower side of the main body 14. Consequently, the chips ofthe workpiece that collide with the main body 14 are prevented frombeing repelled toward the user. Moreover, the guard 50 is provided witha pair of rollers 52 and a front leg portion 54. The pair of rollers 52are positioned more toward the front side than the front leg portion 54.When the user raises the rear grip 28 to the upper side, the pair ofrollers 52 contact the surface of the workpiece and become a fulcrum forangling the engine-driven cutter 10 towards the workpiece. Note that thestructure of the guard 50 is explained in detail later.

The main body 14 comprises a casing 20. The casing 20 is formed from aresin material. The casing 20 comprises a casing main body 26, a filtercover 24, and a top cover 22. The top cover 22 is fixed to the filtercover 24, and the filter cover 24 is fixed to the casing main body 26. Apart of the casing main body 26 is a fuel tank for storing the fuel ofthe engine 18, and is provided with a fuel supplying opening 40 forsupplying the fuel. Moreover, the casing main body 26 is integrallyformed with the rear grip 28 described above, and the internal space ofthe rear grip 28 also constitutes a part of the fuel tank.

FIG. 4 shows the right side of the main body 14. Note that, in FIG. 4, apart thereof is a cross section, and the structure inside the casing 20is shown. As shown in FIG. 4, with the engine-driven cutter 10, the oilsupplying opening 18 a and the oil exhausting opening 18 b are bothprovided on the right side of the main body 14. As described above, ifthe oil supplying opening 18 a and the oil exhausting opening 18 b areboth provided on the same side of the main body 14, the user can replacethe engine oil without having to change the direction of theengine-driven cutter 10 or change one's position relative to theengine-driven cutter 10. Moreover, since the oil supplying opening 18 aand the oil exhausting opening 18 b can be visually confirmedsimultaneously, it is possible to prevent a mistake such as continuingto supply the engine oil from the oil supplying opening 18 a whileforgetting to close the oil exhausting opening 18 b. In addition, sincethe oil supplying opening 18 a and the oil exhausting opening 18 b aredisposed on the right side (driving side) of the main body 14, the oilsupplying opening 18 a and the oil exhausting opening 18 b will not getin the way of the user positioned on the opposite left side (user side).

In addition to the above, with the engine-driven cutter 10, the recoilstarter 44, the starter lever 42, and the fuel supplying opening 40 arealso provided on the right side (driving side) of the main body 14.Accordingly, existence of the recoil starter 44, the starter lever 42,and the fuel supplying opening 40 will not get in the way of the userpositioned on the opposite left side (user side). Accordingly, with theengine-driven cutter 10 of this embodiment, the oil supplying opening 18a, the oil exhausting opening 18 b, the recoil starter 44, the starterlever 42, and the fuel supplying opening 40 are all provided on theright side (driving side) of the main body 14 where the cutter arm 56 ispositioned. Accordingly, as shown in FIG. 2, a large concavo-convex doesnot exist on the left side (user side) of the main body 14 in comparisonto the right side (driving side) of the main body 14. Consequently, theuser can comfortably perform operations without having to mind theconcavo-convex of the main body 14.

The internal structure of the casing 20 is now explained. As shown inFIG. 4, a flow path shown with arrow F in FIG. 4 is formed in the casing20, and the structure is such that the air introduced from the intakewindow 22 a of the top cover 22 passes through the casing 20 and issupplied to the engine 18 via an intake connecting tube 62. The casing20 is internally provided with a pre-filter 68, a main filter 70, and acarburetor 74 along the foregoing flow path F. The pre-filter 68 ispositioned between the top cover 22 and the filter cover 24, and themain filter 70 is positioned between the filter cover 24 and the casingmain body 26. Thus, the pre-filter 68 is positioned at the upper side ofthe main filter 70 in a state where the engine-driven cutter 10 ismounted on the horizontal plane H. The air introduced from the intakewindow 22 a passes through the pre-filter 68 and the main filter 70 inthat order, and the dust contained therein is removed (or filtered).Here, after the air passes through from the lower side to the upper sideof the pre-filter 68, it flows along the inner surface of the top cover22 and the filter cover 24, and passes through the main filter 70 afterchanging its direction of flow approximately 270 degrees.

The air that passed through the main filter 70 subsequently passesthrough the carburetor 74. The carburetor 74 mixes the air that passedthrough the main filter 70 with the fuel. The carburetor 74 is ageneral-purpose carburetor, and includes a throttle valve, a checkvalve, an air vent and the like. The air that was mixed with the fuel inthe carburetor 74 (so-called air-fuel mixture) passes through the intakeconnecting tube 62 is supplied to the engine 18. Note that the intakeconnecting tube 62 is positioned outside of the casing 20. Moreover,FIG. 4 shows the breathing tube 64 at the upper side of the intakeconnecting tube 62. The breathing tube 64 extends from the engine 18,and is connected to an oil separator 82 described later. Note that thebreathing tube 64 is a pipeline for eliminating blow-by gas dischargedinside the locker cover within the engine 18, and is connected to acirculatory path of the engine oil including a crank casing within theengine 18.

The engine-driven cutter 10 of this embodiment adopts the four-strokeengine 18. With the four-stroke engine, the intake port is provided inthe cylinder head, and the carburetor 74 connected to the intake port ispositioned relatively on the upper side. Thus, if the main filter 70 ispositioned at the upper side of the carburetor 74, the main filter 70will protrude considerably toward the upper side relative to the engine18, and the height of the engine-driven cutter 10 is increased. Thus,with the engine-driven cutter 10 of this embodiment, as shown in FIG. 4,the main filter 70 and the carburetor 74 are arranged to align on astraight line along the direction of flow of the air passing through themain filter 70 and the carburetor 74. Specifically, the carburetor 74 ispositioned at the rear side of the engine 18 and the main filter 70 ispositioned at the rear side of the carburetor 74. According to this kindof arrangement and structure, even if the four-stroke engine 18 isadopted, the height of the engine-driven cutter 10 can be keptrelatively small.

As shown in FIG. 4, with the engine-driven cutter 10 of this embodiment,a relatively large main filter 70 is adopted, and a part of the mainfilter 70 is protruding toward the upper side of the rear grip 28.Consequently, the rear surface of the casing 20 (portion of the filtercover 24) is also protruding in a convex shape at the upper side of therear grip 28. Accordingly, if a part or the entirety of the main filter70 is disposed to protrude up reaching the upper side of the rear grip28, a large main filter 70 can be mounted. As a result of mounting thelarge main filter 70, the main filter 70 does not clog easily, and theuser needs to clean the main filter 70 less frequently. Note that, evenif the rear surface of the casing 20 protrudes in the convex shape atthe upper side of the rear grip 28, it will not interfere with theuser's hand that will grasp the rear grip 28. If such interferencebecomes a problem, the angle of the rear grip 28 may be adjusted.

Note that, with the conventional engine-driven cutter, the two-strokeengine is adopted. With the two-stroke engine, the intake port isprovided in the cylinder block and the carburetor connected to theintake port is positioned relatively low. Consequently, with theconventional engine-driven cutter, the main filter 70 is disposed at theupper side of the carburetor 74, and the downsizing of the engine-drivencutter is thereby being sought (for example, refer to Japanese PatentApplication Publication No. 2007-528792).

As shown in FIG. 4, with the engine-driven cutter 10, when theengine-driven cutter 10 is mounted on the horizontal plane H, the designis such that a central axis C of the cylinder of the engine 18 is angledtowards the carburetor 74 relative to a vertical direction V. If theengine 18 is disposed as described above, the carburetor 74 and the mainfilter 70 connected to the engine 18 can be positioned even lower.Consequently, the height of the engine-driven cutter 10 can be reduced.In addition, since the four-stroke engine includes a valve operatingmechanism above the cylinder head and the oil pan below the crankcasing, its height is relatively great in comparison to the two-strokeengine, and there is a possibility that this may cause the enlargementof the engine-driven cutter 10. With respect to this point also, if theengine 18 is angled and positioned as described above, the engine-drivencutter 10 can be designed to be compact.

As shown in FIG. 4 and FIG. 5, a filter bracket 72 is provided betweenthe main filter 70 and the carburetor 74. The filter bracket 72 guidesthe air that passed through the main filter 70 to the carburetor 74. Thefilter bracket 72 is fixed to the casing main body 26, and retains themain filter 70 at a fixed position.

As shown in FIG. 5 and FIG. 6, the filter bracket 72 is fixed to thecasing main body 26 together with the filter cover 24 with a mutual bolt84. According to this structure, it is possible to simplify thestructure and reduce the number of components in comparison to thestructure where the filter bracket 72 and the filter cover 24 areseparately fixed, and the further downsizing of the engine-driven cutter10 can be sought. In addition, the assembly process of the engine-drivencutter 10 can be simplified. Note that, although not shown in FIG. 4 andFIG. 5, as described later, the carburetor 74, the carburetor mount 66,the intake connecting tube 62 and the like are assembled to the filterbracket 72 in advance. Moreover, a main filter 70 is disposed betweenthe filter cover 24 and the filter bracket 72 upon the assembly thereof.

As shown in FIG. 4, the casing 20 includes a carburetor mount 66 towhich the carburetor 74 is fixed. The carburetor mount 66 is mounted ona notch portion 26 a of the casing main body 26 shown in FIG. 4 and FIG.5, and configures a part of the outer wall of the casing 20. Thecarburetor mount 66 is mounted on the casing main body 26 via a sealmember 76. The seal member 76 is an elastic member formed with amaterial with elasticity. In this embodiment, as one example, the sealmember 76 is formed with a polymer material (more specifically a rubbermaterial). The carburetor mount 66 can be displaced relative to thecasing main body 26 based on the deformation of the seal member 76.

FIG. 7 shows a group of components that is assembled to the carburetormount 66. As shown in FIG. 7, the filter bracket 72 and the intakeconnecting tube 62 are assembled to the carburetor mount 66 in additionto the carburetor 74. Here, the filter bracket 72 and the carburetor 74and the carburetor mount 66 and the intake connecting tube 62 aremutually assembled with a mutual bolt 80. Note that a gasket 78 isdisposed between the filter bracket 72 and the carburetor 74 uponassembling the foregoing group of components, and a seal member 76 isdisposed at the peripheral edge of the carburetor mount 66.

As shown in FIG. 7, the carburetor mount 66 includes two supporting beamportions 66 b protruding toward the carburetor 74. The supporting beamportions 66 b support the carburetor 74 from the bottom and retain thecarburetor 74 at the assembly position upon assembling the filterbracket 72 to the carburetor mount 66 with the carburetor 74 interposedtherebetween. As a result of the supporting beam portion 66 b retainingthe carburetor 74, the operator to perform such assembly can easilyperform the assembly process without having to support the carburetor 74with one's hand.

As shown in FIG. 7, the carburetor mount 66 is formed with a recessportion 66 c. The recess portion 66 c is formed on a surface that ispositioned on the side of the carburetor 74. As shown in FIG. 8, therecess portion 66 c faces the arm 74 c that opens and closes thethrottle valve of the carburetor 74, and prevents the arm 74 c fromcontacting the carburetor mount 66. As described above, as a result offorming the recess portion 66 c in a range facing the arm 74 c, thespace between the carburetor mount 66 and the filter bracket 72 can bedesigned to be narrow, and the downsizing of the engine-driven cutter 10can thereby be sought.

The filter bracket 72 is fixed to the carburetor mount 66 with thecarburetor 74 interposed therebetween as shown in FIG. 7, and thereafterfixed to the casing main body 26 as shown in FIG. 5 and FIG. 6. Here,the carburetor mount 66 is mounted on the notch portion 26 a of thecasing main body 26 via the seal member 76. Accordingly, even if thereis a dimension error in the filter bracket 72, the casing main body 26,and the carburetor mount 66, the filter bracket 72 can be properly fixedto the casing main body 26 by the carburetor mount 66 subordinatelydisplacing in accordance with the casing main body 26 to compensate forthe dimension error.

FIG. 9 and FIG. 10 show a connection relationship concerning a flow pathconstituted of the filter bracket 72, the carburetor 74, the carburetormount 66, and the seal member 76. As shown in FIG. 9 and FIG. 10, whenthe filter bracket 72 is assembled to the carburetor mount 66 with thecarburetor 74 intervening therebetween, an opening 72 a of the filterbracket 72 is connected to an opening 66 a of the carburetor mount 66via a main path 74 a of the carburetor 74.

As shown in FIG. 9 and FIG. 10, an oil separator 82 is integrally formedto the filter bracket 72. Moreover, the oil separator 82 is protrudingfrom the filter bracket 72 towards the carburetor 74. In a case wherethe structure is such that the oil separator 82 protrudes towards themain filter 70, it is not possible to prevent the oil separator 82 frominterfering with the main filter 70, and it is necessary to design thefilter bracket 72 to be sufficiently larger than the oil separator 82.Meanwhile, if the structure is such that the oil separator 82 protrudestoward the carburetor 74, the oil separator 82 can be easily provided ata position that does not interfere with the carburetor 74 without havingto enlarge the filter bracket 72.

As shown in FIG. 9 and FIG. 10, the seal member 76 is formed with twothrough holes 76 a. The position of the two through holes 76 acorresponds to the position of two nipple portions 82 a of the oilseparator 82. Here, the nipple portion 82 a of the oil separator 82 is aconnecting opening that protrudes in a tubular shape with a rib, and thethrough hole 76 a of the seal member 76 is a receiving opening forreceiving the nipple portion 82 a. Note that a periphery 76 b, 76 c ofthe through hole 76 a is protruding in a tubular shape by a rib at thefront and back of the seal member 76. According to the foregoingconfiguration, when the filter bracket 72 is assembled to the carburetormount 66 with the carburetor 74 interposed therebetween, as shown inFIG. 11, the respective nipple portions 82 a of the oil separator 82 areautomatically connected to the corresponding through holes 76 a of theseal member 76 from the inside of the casing 20. Subsequently, when therespective breathing tubes 64 are connected to the through holes 76 a ofthe seal member 76 from the outside of the casing 20, and the oilseparator 82 and the breathing tube 64 become mutually connected via thethrough holes 76 a. As described above, according to the structure ofthis embodiment, the troublesome process of connecting the oil separator82 to the breathing tube 64 within the limited space in the casing 20 isno longer required. Note that, as shown in FIG. 11, the breathing tube64 is connected to the through hole 76 a of the seal member 76 via ajoint 65. However, the breathing tube 64 may also be connected directlyto the through hole 76 a of the seal member 76 without using the joint65.

As shown in FIG. 10, the carburetor 74 is provided with a hose nipple 74b connected to an air vent. The distal end of the hose nipple 74 bextends toward the filter bracket 72. Meanwhile, the filter bracket 72is provided with an air vent connecting opening 72 b at a positioncorresponding to the hose nipple 74 b. According to the foregoingstructure, when the filter bracket 72 is assembled to the carburetormount 66 with the carburetor 74 interposed therebetween, the hose nipple74 b of the carburetor 74 is automatically connected to the air ventconnecting opening 72 b of the filter bracket 72. Accordingly, thetroublesome processing of connecting the host nipple 74 b of thecarburetor 74 to the air vent connecting opening 72 b of the filterbracket 72 using a tube or the like within the limited space in thecasing 20 is no longer required.

The assembly structure of the throttle lever 30 and the switch lever 32is now explained with reference to FIG. 4, FIG. 12, and FIG. 13. Asshown in FIG. 4, the throttle lever 30 is supported with the shaft 34,and is swingable around the shaft 34. The throttle lever 30 is connectedto the throttle valve of the carburetor 74 via a link 30 a. Moreover,the switch lever 32 is also mounted on the same shaft 34 in addition tothe throttle lever 30. The switch lever 32 is also swingable around theshaft 34. The switch lever 32 is connected to the choke valve of thecarburetor 74 via the link 32 a.

FIG. 12 shows a state where the throttle lever 30 and the switch lever32 are assembled to the casing main body 26, and FIG. 13 shows a statewhere they are disassembled. As shown in FIG. 12 and FIG. 13, the casingmain body 26 is formed with a shaft receiving groove 26 b extending inthe axial direction of the shaft 34. The shaft receiving groove 26 bretains the shaft 34 from its radial direction. Since the upper side ofthe shaft receiving groove 26 b is open, the shaft 34 can be easilyfitted into the shaft receiving groove 26 b. In particular, the shaft 34can be fitted into the shaft receiving groove 26 b in a state where thethrottle lever 30, a spring member 30 b, and the switch lever 32 aremounted on the shaft 34 in advance.

Here, when the user operates the throttle lever 30 or the switch lever32, the respective levers 30, 32 apply downward force to the shaft 34.Meanwhile, the opening direction of the shaft receiving groove 26 b isfacing the upper side. Accordingly, since the opening direction of theshaft receiving groove 26 b and the direction that the shaft 34 receivesthe force from the respective levers 30, 32 are mutually different, theshaft 34 is securely retained by the shaft receiving groove 26 b, andthe behavior of the respective levers 30, 32 is thereby stabilized.

In addition, with this embodiment, the shaft receiving groove 26 b isdivided into two sections, and the structure is such that a spacesurrounding the shaft 34 is formed between the two shaft receivinggrooves 26 b. Accordingly, if the structure is such that one or moreshaft receiving grooves 26 b are provided only in the lengthwisedirection of a part of the shaft 34, and space is formed around theshaft 34 in a remaining lengthwise range, the shaft 34 that is mountedon the shaft receiving grooves 26 b can be easily removed.

As shown in FIG. 12 and FIG. 13, the filter bracket 72 is formed with ashaft holding portion 72 e at two locations. The shaft holding portions72 c come in contact with the shaft 34 retained by the shaft receivinggrooves 26 b from the opening direction of the shaft receiving grooves26 b (upper side in this embodiment). According to this structure, it ispossible to prevent the shaft 34 retained by the shaft receiving grooves26 b from moving or coming loose from the shaft receiving grooves 26 bwithout having to provide a separate member for holding the shaft 34.Moreover, as a result of the filter bracket 72 fixed to the casing mainbody 26 coming in contact with the shaft 34 similarly supported by thecasing main body 26, the filter bracket 72 also functions as a supportpillar (or beam) within the casing 20, and is able to significantlyimprove the rigidity of the casing 20.

As shown in FIG. 12 and FIG. 13, the casing main body 26 is providedwith a pair of shaft position determining portions 26 c respectivelyfacing the respective ends of the shaft 34. According to this structure,it is possible to prevent the shaft 34 retained by the shaft receivinggrooves 26 b from moving in the axial direction and coming loose fromthe shaft receiving grooves 26 b without having to provide a retainingmember such as a circlip to the shaft 34.

The configuration of the guard 50 is now explained with reference toFIG. 14 to FIG. 19. FIG. 14 is a diagram showing the right side of theguard 50, FIG. 15 is a diagram showing the front side of the guard 50,and FIG. 16 is a diagram showing the lower side of the guard 50.Moreover, FIG. 17 is a cross section of line XVII-XVII in FIG. 14, andFIG. 18 is a cross section of line XVIII-XVIII in FIG. 16. FIG. 19 showsa state where a workpiece W is being cut with the engine-driven cutter10. Here, a straight line S in the drawings shows a rotating plane ofthe disk blade 12. The rotating plane S is a virtual plane where therotating disk blade 12 is positioned, and is a plane that isperpendicular to the rotating axis of the disk blade 12 and whichincludes the disk blade 12. However, since the disk blade 12 has alimited thickness, the rotating plane S is defined to match the positionof one end surface of the disk blade 12. Moreover, an arrow D in FIG. 19shows the path that the chips of the workpiece W will scatter.

The guard 50 comprises a guard surface 90, a pair of rollers 52, and afront leg portion 54. The front leg portion 54 is molded such that itscorner portion 54 a is formed as a curved surface so that the user caneasily angle the engine-driven cutter 10. The pair of rollers 52 isdisposed coaxially with the rotating plane S of the disk blade 12interposed therebetween, and the rotating axis thereof is parallel tothe rotating axis of the disk blade 12. The guard surface 90 is providedbetween the pair of rollers 52. The guard surface 90 is a groove-shapedcurved surface formed on the guard 50, and extends along the rotatingplane S of the disk blade 12.

As shown in FIG. 18, the guard surface 90 has a tilted surface whichbasically faces obliquely downward toward the front side. Specifically,the guard surface 90 is tilted to be apart from the surface of theworkpiece as the front side position is closer to the disk blade 12. Theguard surface 90 repels the chips of the workpiece that scattered fromthe disk blade 12 toward the lower side of the main body 14.Consequently, it is possible to prevent the chips of the workpiece thatscattered from the disk blade 12 in the main body 14 from being repelledtoward the user. Note that the guard 50 is formed with a plurality ofpositioning protrusions 50 a, and is configured so that it can be easilyassembled to the main body 14. Here, the guard surface 90 can be formedas a surface that is free from concavo-convex or a surface with littleconcavo-convex so that the chips of the workpiece are smoothly guided tothe lower side of the main body 14. However, in another embodiment,grooves and protrusions may be intentionally provided for guiding thechips of the workpiece to a specific direction.

The guard surface 90 has different shapes in a left side (user side)range 90 a and a right side (driving side) range 90 b with the rotatingplane S as the boundary. Specifically, the guard surface 90 has anasymmetric shape with the rotating plane S as the boundary.Consequently, the guard surface 90 repels the chips scattered from thedisk blade 12 asymmetrically to the rotating plane S of the disk blade12.

In particular, with the guard surface 90 of this embodiment, as shown inFIG. 17, the normal vector N is tilted toward the rotating plane S so asto face the rotating plane S in the entire left side (user side) range90 a. To express this differently, in the left side (user side) range 90a of the guard surface 90 formed in a groove shape, the depth becomesnarrow as it becomes separated from the rotating plane S. Accordingly,in the left side (user side) range 90 a, the chips that scattered fromthe disk blade 12 are repelled toward the rotating plane S.Specifically, the chips that scattered from the disk blade 12 to theleft side (user side) can be repelled toward the right side (drivingside). Consequently, many of the chips that scattered from the diskblade 12 are repelled to the right side (driving side) of the main body14. The user can use the engine-driven cutter 10 comfortably withoutbeing obstructed with the chips as a result of positioning oneself onthe left side (user side) as the opposite side.

The shape of the guard surface 90 described above is an example, and theshape of the guard surface 90 is not limited thereto. The shape willsuffice so as long as a majority of the chips that scattered from thedisk blade 12 can be repelled to the right side (driving side) of themain body 14, and, for example, the angle, depth, and area of the guardsurface 90 may be changed between the left side (user side) range 90 aand the right side (driving side) range 90 b.

As shown in FIG. 19, the user can move the engine-driven cutter 10 alongthe surface of the workpiece W in a state of causing the pair of rollers52 to come in contact with the surface of the workpiece W and anglingthe engine-driven cutter 10 towards the surface of the workpiece W.Here, even if there is an obstacle (for instance, a fragment of theworkpiece W or a protrusion of the workpiece W) on the surface of theworkpiece W, it is possible to go over the obstacle by angling the guardsurface 90. In particular, with the engine-driven cutter 10 of thisembodiment, the pair of rollers 52 are used as the fulcrum, and, evenwhen the engine-driven cutter 10 is fully angled towards the surface ofthe workpiece W (state of FIG. 19), the guard surface 90 is tilted tobecome separated from the surface of the workpiece W as it approachesthe disk blade 12 (front side). Specifically, a height T from thesurface of the workpiece W to the guard surface 90 becomes higher as itapproaches the disk blade 12 (front side). According to this structure,regardless of the angle when the engine-driven cutter 10 is angledtowards the surface of the workpiece W, it is possible to go over theobstacle existing on the surface of the workpiece W based on the tilt ofthe guard surface 90.

1. A handheld engine-driven cutter comprising: a disk blade; and a mainbody that drives the disk blade, the main body comprising: a four-strokeengine; an oil supplying opening from which engine oil is supplied; andan oil exhausting opening from which the engine oil is exhausted,wherein the oil supplying opening and the oil exhausting opening aredisposed on one side of the main body.
 2. A handheld engine-drivencutter as in claim 1, wherein the main body further comprises a fuelsupplying opening from which fuel is supplied, and the fuel supplyingopening is also disposed on the one side of the main body.
 3. A handheldengine-driven cutter as in claim 1, wherein the main body furthercomprises a starter member that is operated by a user to start thefour-stroke engine, and the starter member is also disposed on the oneside of the main body.
 4. A handheld engine-driven cutter as in claim 1,wherein the main body further comprises a transmission mechanism thatsupports the disk blade and transmits torque from the four-stroke engineto the disk blade, and the transmitting mechanism is also disposed onthe one side of the main body.
 5. A handheld engine-driven cutter as inclaim 2, wherein the main body further comprises a starter member thatis operated by a user to start the four-stroke engine, and the startermember is also disposed on the one side of the main body.
 6. A handheldengine-driven cutter as in claim 5, wherein the main body furthercomprises a transmission mechanism that supports the disk blade andtransmits torque from the four-stroke engine to the disk blade, and thetransmitting mechanism is also disposed on the one side of the mainbody.
 7. A handheld engine-driven cutter as in claim 3, wherein the mainbody further comprises a transmission mechanism that supports the diskblade and transmits torque from the four-stroke engine to the diskblade, and the transmitting mechanism is also disposed on the one sideof the main body.